I've never seen an official list for the unofficial & silly holidays so I've always just searched for "holiday list" or something similar and go with what ever pops up at the time (http://www.holidayinsights.com/moreholidays/ this time around). It doesn't have the cat day one listed though.

But doing a search for the cat day and "holiday list" comes up with this page (http://www.checkiday.com/) which may be more what you're looking for.

When I was working on the radio, it seemed every Promotions Director (cool title, eh?) had a copy of Chase's Calendar of Annual Events, which in the 1970s had Holidays around the world, anniversaries, birthdays, events and festivals for every day of the year, ran 150 pages and cost about $15. Today it's Idon'tknowhowmany pages but contains over 12,000 entries and costs $80 (book and CD-ROM, but the publisher's site gives you a sample of the next two days, and there's an abbreviated on-line list (PDF) with the same name.

Wikipedia has a lot of info on individual days; here's November 1st...
50 Years Ago Today, The Arecibo Observatory in Arecibo, Puerto Rico, with the largest radio telescope ever constructed, officially opened and the 1963 South Vietnamese coup began.
French King Louis the Stammerer was born on this date in 846; it's Kinky Friedman's 69th birthday and Lyle Lovett's 56th, while Yma Sumac died five years ago this date.
Of course, this is All Saints Day, but also Independence Day for Antigua and Barbuda and World Vegan Day.
And Wikipedia also links to The New York Times' On This Day and BBC's On This Day (which may not have been updated since 2005), which are Historical Event-oriented and not Holidays and Observances.